If you've ever looked under the bonnet of a car, the engine can seem like a maze of metal parts, pipes and wires. In reality, its job is quite simple: it turns fuel into the power that moves your car.

How boxer engines work, why they’re not just “flat” engines, and a 120-year evolution traced from the 1899 Benz to the latest Porsche and Subaru boxers. Boxer engines feature flat, opposing pistons ...